1. Field of the Invention
The present invention relates to a method of preparing high purity, anhydrous alkali metal salts of the inorganic-alkali metal type. More particularly, the present invention is directed to the method of preparing such compounds by reacting specified nitrogen-containing compounds with specified alkali metal-containing compounds, as more fully developed below.
2. Description of the Prior Art
There have been many techniques developed over the past few years for the synthesis of inorganic--as well as organic--alkali metal salts. For example, Kunze et al, J. Phys. Chem. 67, 385 (1963) describe the preparation of lithium tetraphenyl boride by the reaction of sodium tetraphenyl boride with lithium chloride in ethanol, and Bhattacharyya et al, J. Phys. Chem. 69, 608 (1965) describe the preparation of alkali metal tetraphenyl boride salts by the reaction of sodium tetraphenyl boride with lithium chloride in THF solvent. Revzin et al, Chemical Abstracts 70, 28974 q (1969) and Chemical Abstracts 71, 3416 s (1969) describe the preparation of lithium tetraphenyl boride from various salts, including ammonium tetraphenyl boride with lithium-containing ion exchange resins in acetone. Likewise, Kirgintsev et al, Chemical Abstracts 72, 139078 m (1970) describe the formation of lithium tetraphenyl borate and sodium tetraphenyl borate using potassium tetraphenyl borate with an ion exchange resin of the lithium form and using acetone solvent. Kozitskii, Chemical Abstracts 79, 83825 c (1973) describe the preparation of lithium tetraphenyl borate and the like by reaction of the potassium analogue with a lithium-containing ion exchange resin in the presence of acetone and water. (It should be noted that various prior art references refer to the same compounds as tetraphenyl borate or as tetraphenyl borides). Khol'kin et al, Chemical Abstracts 85, 86471 u (1976) describe the preparation of lithium tetraphenyl boride from sodium tetraphenyl boride but do not describe the source of lithium except to point out that it is an exchange synthesis, i.e., exchange extraction synthesis. Witting et al, Ann. 563, 110 (1949) and Chemical Abstracts 46, 6607 d (1952) respectively teach the preparation of lithium tetraphenyl boride and the like from triphenyl boron and trifluoro boron sources reacted with lithium phenyl salt in ether solvents. Grassberger et al, Angew. Chem. Int. Ed. Engl. 8, 275 (1969) describe the preparation of various alkali metal tetraorganyl borates by reaction of, for example, triphenyl boron with lithium tetraethyl boride without solvent.
Lee, Inorg. Chem., Volume 3, No. 2, February 1964, pp. 289-90 describes the synthesis of lithium thiocyanate from hydrated lithium hydroxide and ammonium thiocyanate. Olah et al, Journal of the American Chemical Society, 97, No. 12, pp. 3559-3561 (1975) describe the synthesis of LiO.sub.2 CCF.sub.3 from lithium hydride and NH.sub.4 0.sub.2 CCF.sub.3. Morosi et al, Chemical Physics Letters, Volume 47, No. 2, pp. 396-398 (1977) describe a theoretical analysis of a hypothetical reaction between the ammonium ion and lithium hydride in the gas phase to yield lithium salts. U.S. Pat. No. 3,049,406 describes the preparation of anhydrous lithium salts, including lithium halides, lithium pseudohalides, such as lithium cyanide and lithium thiocyanate, by the reaction of lithium hydride with halogens, cyanogen or thiocyanogen in an ether solution.
Notwithstanding all of the aforementioned prior art directed to various methods of preparing alkali metal salts, to date no reference has been published which teaches or renders obvious the methods of preparation described herein.